This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To determine the phenotypic and functional evaluation of decidual immune cells in the cynomolgus and vervet (African green) monkeys. The decidua is a specialized adaptation of the uterine endometrium to support the implanting embryo in primate pregnancy. Non-human primates are the important animal models for the study of maternal immune response within decidua to fetal development. Early pregnancy cynomologus and vervet deciduas were obtained by cesarean section. Lymphocytes were isolated by enzymatic dispersion and gradient centrifugation. Multi-color flow cytometry was used to phenotype cell populations, chromium release assay was used to evaluate cytotoxic activity of NK cells. NK cells were found as the richest lymphocyte population in the monkeys deciduas and the majority were CD56 bright cells, like human decidual NK (dNK) cells. Peripheral NK (pNK) cells in cynomolgus and vervet, in contrast to human, do not express CD56, suggesting the influence of a unique decidual environment to promote NK cell differentiation. While human CD56+ dNK cells are CD16-, more then 70% of monkeys'CD56+ dNK cells remained CD16+. Intracellular staining with anti-perforin mAbs demonstrated that dNK cells contain this protein. However, the cytotoxic potential was not apparent in chromium assay;CD56+ cells from cynomolgus decidua showed strongly reduced cytolytic activity against target cells when compared to pNK cells. Approximately 10% of decidual leukocytes are T cells. Most decidual T cells in cynomolgus and vervet were phenotyped as cytotoxic CD8+ cells (about 70%) and 2-15% co-expressed the NK cell marker CD56 (NKT cells). Together, these results showed that cynomolgus and vervet maternal-fetal interfaces are very rich in immune cells. Lymphocytes populations'diversity in monkeys'deciduas correlate with human studies, confirming that both species are excellent models for study mechanisms of immune recognition and tolerance that support primate pregnancy. This research used WNPRC Animal, Research, Assay, and Immunology &Virology Services. Funding ended before this reporting period began;publications have resulted. PUBLICATIONS: Bondarenko G.I., Dambaeva S.V., Grendell R.L., Hughes A.L., Durning, M., Garthwaite M.A., and Golos T.G. 2009. Characterization of cynomolgus and vervet monkey placental MHC class I expression: Diversity of the nonhuman primate AG locus. Immunogenetics 61:431-442. Dambaeva, S.V., Breburda, E.E., Durning, M., Garthwaite, M.A., Golos, G.G. 2009. Characterization of cynomolgus and vervet monkey decidual leukocyte populations. J. Reprod. Immunol. 80:57-69.